In the airline world evacs are initiated from the cockpit in case you didn't know. You can ask during your next recurrent if you don't believe me. It is part of the checklists and everybody, including the flight attendants, are trained on it. Unless I hear otherwise that is what I am going to expect what happened. The only time in the past when a passenger or FA initiated an evacuation without orders from the cockpit there was always fire or smoke involved. As far as I know there were none in this case.